RISK-BASED ADAPTIVE SCREENING FOR CERVICAL CANCER

Purpose: U.S. guidelines recommend Pap testing every three years for routine screening of women aged 21 to 65 years.  However, studies suggest that screening results can be predictive of differential cervical cancer risk for up to 10 years, which may warrant screening algorithms that dynamically adjust according to risk.  We investigated a risk-based adaptive screening program for cervical cancer in which screening intervals were adjusted based on initial Pap result.

Method: We used a microsimulation model of cervical cancer natural history and screening to compare the health and economic consequences associated with alternative adaptive screening approaches for women aged 21 to 65 years.  Current guidelines-based screening involving Pap testing every three years was compared to alternative adaptive strategies that extend the routine screening interval to every 5-, 7- or 10-years for women with a negative Pap test.  Follow-up of abnormal Pap testing was consistent with current guidelines for diagnosis and treatment of cervical disease.  Risk-based input parameters were based on a large-scale population-based study (n > 300,000).   

Result: Compared to current guidelines-based screening, the proposed adaptive strategies resulted in far greater reductions in lifetime costs than in cancer benefit. For example, moving from universal 3-year screening to a 5-year interval for women with a negative Pap test resulted in a 51% (approx. $900 per person screened woman) reduction in costs accompanied by a 0.12% absolute increase in cervical cancer risk.  Extending the screening interval to 7 years for women with a negative Pap screen reduced costs by 55% and increased risk by 0.24%, while extending screening to 10 years reduced costs by 57% and increased risk by 0.71%.  

Conclusion: Risk-based adaptive screening strategies can yield significant cost reductions but with slightly higher risks of cancer, compared to current guidelines.  Further analysis should evaluate whether the savings from decreasing the total number of screens in a population may be used to increase screening of high-risk patients to offset the higher cancer risk and improve screening efficiency. Analyses should also include potential gains in decreasing cases of over-diagnosis with adaptive screening.  Overall, risk-based adaptive screening accounts for population heterogeneity in modeling to improve the efficiency of screening and significantly decrease the burden of screening program costs on the healthcare system.